Control system for clothes dryers



R. L. DUNKELMAN 2,851,789

CONTROL SYSTEMVFOR CLOTHES DRYERS Sept. 16, 1958 Filed March 13, 1956 2Sheets-Sheet 1 2 l 1 m. H'. gsm'm FIG. 5 J i 7 3 ROBERT L. DUNKELMANSept. 16, 1958 R. L. DUNKELMAN 2,851,789

CONTROL SYSTEM FOR CLOTHES DRYERS Filed March 13, 1956 2 Sheets-Sheet 2IL IL 0 m :0 -5 &

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HIS ATTORNEY United States Patent Ofiice CONTROL SYSTEM FOR CLOTHESDRYERS Robert L. Dunkelman, Shreveport, La., assignor to GeneralElectric Company, a corporation of New York Application March 13, 1956,Serial No. 571,181

12 Claims. (Cl. 34-45) My invention relates to clothes dryers and moreparticularly to the electrical control systems used in such dryers.

It is an object of my invention to provide a new and improved controlsystem for clothes dryers.

It is another object of my invention to provide an improved controlsystem for clothes dryers, by which the drying operation may becontrolled in accordance with the temperatures of both the inlet airentering the clothes tumbling means and the exhaust air leaving thetumbling means, thereby automatically to terminate the dryer operationwhen the clothes have dried.

A further object of my invention is to provide a clothes dryer controlsystem which is effective selectively to produce at least two diiferentdrying operations including the above mentioned automatic temperaturecontrolled drying operation and also a second drying operation of timedlength.

Another object of my invention is to provide a clothes dryer controlsystem which is effective to produce three different clothes treatingoperations comprising the automatic temperature controlled dryingoperation, the drying operation of timed length, and a clothes tumblingoperation without heat also of timed length.

Still another object of my invention is to provide a control system ofthis latter type in which the dryer heater may be selectively energizedat a plurality of different levels during the timed drying operation. Itis an additional object of my invention to provide a control system ofthat type, which may be adjusted simply and easily between its variousoperations by means of a single rotatable control dial and a pluralityof push buttons.

Still a further object of my invention is to provide an improved clothesdryer control system having a motor driven centrifugal safety switch inthe heater circuit, which switch is also utilized to open the timermotor circuit when the drive motor stops at the end of one of the dryingoperations of the system.

In carrying out my invention in one form thereof, I provide a clothesdryer including clothes tumbling means and a drive motor for driving thetumbling means. A heater is provided within the machine, and blowermeans are arranged for blowing air over the heater and through thetumbling means for drying the clothes therein. By my invention a new andimproved control system is incorporated within the dryer for obtainingthree different operations therefrom, namely -a clothes drying operationof timed length, a temperature controlled drying operation whereinoperation is terminated automatically when the clothes have dried, and atimed clothes tumbling operation wherein the clothes are tumbled withoutheat. My improved control system includes a motor driven timer, a heatercycling thermostat responsive to the temperature of the inlet airentering the tumbling means from the heater, and a second thermostatresponsive to the temperature of the exhaust air leaving the tumblingmeans. The system utilizes these three elements and a plurality ofcircuits to produce the three different operations.

The circuits of the control system all include switch means operated bythe timer, which must be closed to start the various operations andwhich terminate the operations when they are opened. The heater isenergized by a circuit through the heater cycling thermostat, whichcircult is closed for the clothes drying operations and which is openfor the clothes tumbling operation. The drive motor is energized by acircuit which is closed for all three operations. Two different circuitsare provided for energizing the timer to determine the length of thevarious operations. By the one circuit the timer is energizedcontinuously and this circuit is utilized to produce the timed clothesdrying operation and the timed clothes tumbling operation. controlled byboth the exhaust thermostat and the heater cycling thermostat so that itis not energized at the beginning of the operation but rather isenergized only after both the inlet air and the exhaust air reachpredetermined high temperatures. This circuit is utilized to produce thetemperature controlled operation, and it is effective to energize thetimer so that the operation is terminated automatically when the clotheshave dried. The control is selectively adjusted to close the variouscircuits and produce the diflferent operations by means of suitablemanually operated means which may include a rotatable control dial and aplurality of push buttons.

The subject matter which I regard as my invention is pointed out withparticularity in the appended claims. My invention itself, however, bothas to its organization and method of operation, may be best understoodby reference to the following description taken in conjunction with theaccompanying drawings in which:

Fig. l is a perspective view of a domestic clothes dryer including acontrol system embodying my invention, the view being partially brokenaway in order to show details;

Fig. 2 is a schematic diagram of the control system itself;

Fig. 3 is an enlarged fragmentary view showing the operator controls ofthe control system;

Fig. 4 is a chart showing the sequence of operation of the timeroperated switches included in the system of Fig. 2; and

Fig. 5 is a chart showing the relationship between the push buttons ofthe operator controls and the switches in the control system operatedthereby.

Referring now to Fig. 1 I have shown therein a clothes dryer 1 which isillustrative of the various clothes dryers in which my new and improvedcontrol system may be used. The dryer 1 includes a rotatable drum orbasket 2 which is mounted for rotation about a generally horizontalaxis. The basket 2 is disposed within an outer enclosing cabinetstructure 3, and aligned openings 4 and 5 are provided respectively inthe front walls of the basket and the cabinet structure for the loadingand unloading of the clothes from the basket. The openings 4 and 5 areflanged as shown to prevent clothes from dropping down between thebasket and the cabinet. A door 6 hingedly mounted on the cabinet closesthe opening 5 during the operation of the dryer.

For rotating the basket 2 during operation of the dryer there isprovided an electric motor 7 which is connected to the basket by asuitable belt drive 8. The pulleys (not shown) mounting the belt driveare so arranged that the basket 2 is driven at a suitable speed fortumbling articles of clothing. The basket 2 preferably includesupstanding ribs on the inner surface thereof to aid in producing thetumbling action. Besides driving the basket 2 the motor 7 also serves todrive air moving means for circulating a stream of air through thebasket during the operation of the machine. The air moving meanscomprises a centrifugal blower 9 which is driven by the motor 7 by meansof a direct coupling 10. The blower 9 draws in.

Patented Sept. 16, 1958,

By the second circuit the timer isv 3 air from the surrounding roomthrough a conduit 11 which leads from a screened air inlet opening 12 inthe toeboard 13 of the cabinet.

The air drawn in by the blower 9 is discharged through an opening 14 atthe top thereof into a space 15 which is separated from the rotatingbasket 2 by a baffle 16. As shown, the baflle 16 extends upwardly fromthe base of the machine to a point in the general vicinity of anelectrical heating element 17 mounted at the top of the machine, thebafile 16 being curved arcuately around the perforated side wall 18 ofthe basket for a portion of its length. The air discharged from theblower 9 flows upwardly through the space 15 and passes outwardlytherefrom across the electrical heating element 17. The air still underpressure from the blower then flows downwardly through the foraminatedcylindrical wall 18 of the basket. A generally arcuate baffle orwrap-around 19 confines the flow path of the air so that it ispositively passed through the wall 18 into the basket. The air movesdownwardly through the basket and the articles of clothing being tumbledtherein and next passes into a collecting chamber 20 lying beneath thebasket 2 on the opposite side of the baffle 16 from the space 15. Fromthe chamber 20 the air is discharged out of the cabinet into thesurrounding room through an appropriate lint trap structure 21 mountedin the toe-board 13.

The machine 1 is intended for use both as a clothes drying means and asa clothes sprinkling means. When the machine is to be used as a clothesdryer the heater 17 is energized along with the drive motor 7. Thus theair discharged from space 15 absorbs heat from the heater 17 as itpasses thereover. The heated air then extracts moisture from the clothesbeing tumbled in the drum as it passes therethrough. The heatingelement, however, is not energized when the machine is being used as aclothes sprinkling means. Thus the air passing through the drum is notheated and it does not extract moisture from the clothes. Any suitablemeans may be used to sprinkle the clothes during this operation, but itis preferred to use a container which can be mounted on the drum 2 so asto discharge water onto the clothes at a slow rate as the basketrotates. A suitable container for this purpose is shown and described inthe copending application of Eugene G. Olthuis, Serial No. 430,794 filedMay 19, 1954 and assigned to the same assignee as the present invention.It will be understood, of course, that if the sprinkling means are notmounted within the drum, this clothes tumbling operation of the dryerwithout heat may be used for fiufling previously dried clothes or forany other purpose wherein it is desired to tumble the clothes withoutthe application of heat.

Referring now to Fig. 2 I have shown therein a control system for thedryer 1, which embodies my invention in one preferred form thereof. Thiscontrol system provides for a plurality of different clothes treatingoperations to be carried out within the dryer. It provides for atemperature controlled clothes drying operation wherein the dryer iscontrolled by the temperatures of both the inlet air to the tumblingdrum and the exhaust air leaving the drum so that the drying operationis automatically terminated when the clothes have fully dried. It alsoprovides for a clothes drying operation of timed length wherein thelength of the operation is preset by the operator. In this timed dryingoperation the heater 17 may be selectively energized at two differentlevels to supply heat at a high rate or a lower rate. The controlfurther provides for a clothes tumbling operation of timed lengthwherein the heater is not energized at any time.

In order to time the lengths of the timed clothes drying operation andthe timed clothes tumbling or sprinkling operation, and also in order toterminate the temperature controlled operation when the clothes havefully dried, the control system includes a timer mechanism 22. Thistimer mechanism operates continuously during both the 4 l timed dryingoperation and the timed sprinkling operation, but is controlled by thetemperatures of the inlet and exhaust air of the drum 2 during thetemperature controlled operation so that it begins running only at asuitable time after the operation is initiated to terminate theoperation when the clothes have fully dried. The timer mechanismincludes a timer motor 23 and a plurality of cams 24, 25 and 26 whichare driven by the timer motor through suitable one-way clutch means. Thecams 24, 25 and 26 are arranged to operate switches 27, 28 and 29respectively through suitable cam followers which ride on theirperipheries, and these switches are connected in the control system forcontrolling the heater 17, the drive motor 7 and the timer motor itself.The two switches 27 and 28 are connected respectively in the circuitsfor energizing the heater 17 and the drive motor 7, the switch 27 beingconnected serially in the heater circuit and the switch 28 beingconnected serially in the drive motor circuit. The switch 29 isconnected in one of two alternate circuits for energizing the timermotor 23, which one timer circuit also passes through the switch 28. Thedrive motor circuit, the heater circuit, the two timer motor circuits,and the connection of the switches 27, 28 and 29 in these circuits willbe more fully described hereinafter.

In order that the switch operating cams 24, 25 and 26 may be adjusted toany desired position, the timer mechanism is provided with a rotatabledial 30 which is mounted on the same shaft as the cams. By adjusting thedial 30 and thus the cams 24, 25, and 26, the timer may be set so as toproduce either the automatic temperature controlled drying operation orthe timed clothes drying and clothes sprinkling operations. The timerdial includes two ranges, one for the temperature controlled automaticdrying operation and the other for the two timed operations, with thetwo ranges being separated from each other by suitable off or machineinoperative sectors. Within the time range the selection between dryingand tumbling without heat is made by suitable push buttons as describedbelow. The timer mechanism may be mounted at any suitable point withinthe machine but preferably is mounted on the backsplasher 31 thereof asis shown in Fig. 1.

For determining the length of the automatic drying operation wherein thetimer mechanism 22 is thermostatically controlled, the control systemincludes a pair of thermostats 32 and 33. The one thermostat 32 ispositioned so as to sense the temperature of the inlet air entering thedrum from the heater 17 and the other thermostat 33 is positioned so asto sense the temperature of the exhaust air leaving the drum through thespace 20. These two thermostats are connected in the control system sothat the timer mechanism 22 does not begin to operate during theautomatic drying operation until both the inlet air to the drum and theexhaust air from the drum have reached predetermined high temperatures.In other words the two thermostats control the timer motor to producethis result, and thereby the timer mechanism is made effective toterminate the drying operation at the time the clothes have fully dried.The thermostats may be positioned within the machine in any suitablemanner. For example, the thermostat 32 may be mounted on the wrap around19 and the thermostat 33 may be mounted on a bracket 3 in the exhaustair collecting space.

Besides serving as a portion of the means for controlling the timermechanism during the automatic drying operation, the inlet airthermostat 32 also acts as a heater cycling thermostat. in other wordsit is connected to cycle the heater 17 on and oil in response to thetemperature of the inlet air. As a result of this cycling the inlet airis prevented from rising to a temperature above the temperature safe forsynthetics and other delicate fabrics. In other words the heater cyclingthermostat controls the heater so as to keep the machine temperaturesafe for all kinds of fabrics, and this control is etlectrol.

tive not only during the automatic drying operation but also during thetimed drying operation.

In order to select the desired operation the control system includes aplurality ofpush buttons 35, 36, 37 and 38 in addition to the timer dial30. These push buttons control a plurality of switches 39, 40, 41, 42,and 43 which are connected in the various circuits of the con- Themanner in which the push buttons control the various switches isindicated by the chart of Fig. 5. In this chart an X mark indicates thata switch is closed and a blank indicates that it is open. For example,if the push button 35 is pushed, switches 40 and 42 are closed whileswitches 39, 41 and 43 are opened. Similarly, if the push button 36 isdepressed the switches 39, 41 and 42 are closed while the switches 40and 43 are opened. Since any suitable mechanical linkage may be usedbetween the push buttons and the switches to effect the resultsindicated by this chart, and since the mechanism forms no part of thepresent invention, it has not been illustrated herein.

The manner in which the switches 39-43 are connected in the controlsystem and the results obtained from them are explained in detailhereinafter. Briefly stated, however, the switches 42 and 43 provide forenergizing the heater 17 at two diiferent levels during the time dryingoperation and for disconnecting it completely during the timedsprinkling operation. The switches 44} and 41 provide for energizing thetimer motor 23 through alternate circuits thereby to allow selection ofeither the automatic drying operation or the timed Operations; and theswitch 39 provides a safety.

timer circuit if the operator should depress the wrong push button whenthe dial is set in the automatic range.

To obtain the different operations of the dryer the operator sets thedial 30 and operates one of the push buttons. To obtain the automatictemperature controlled operation of the dryer the operator sets the dialin the automatic range 44 and depresses the auto (automatic) push button35. If she wishes to set the machine for the clothes tumbling orsprinkling operation, the operator sets the dial in the time range 45and depresses the sprinkle push button 38. If she wishes to set the machine for the timed drying operation she sets the .dial in the timerange 45 and depresses either the Hi (high) button 36 or the L (low)button 37. Depressing the button 36 results in the heater beingenergized at its higher level during this operation and the depressingof the button 37 results in the heater operating at its lower levelduring this operation.

To explain in detail the connections and the operation of my improvedcontrol system, let it be assumed that the operator desires to conductan automatic temperature controlled drying operation in the dryer. To dothis she, of course, sets the dial 3!) in the automatic range anddepresses the auto push button 35. As indicated by the cam chart of Fig.4 this setting of the dial 3t) closes the switches 27 and 28 whilecausing the switch 29 to remain pen, and as indicated by the chart ofFig. the depressing of the push button 35 closes switches 40 and 42while opening switches 39, 41 and 43. As a result of these settings thedrive motor is energized by a circuit through the timer operated switch28, and the heater is energized by a circuit through the timer operatedswitch 27, the heater cycling thermostat 32 and the manually operatedswitch 42. A circuit is also set up for energizing the timer motor 23,but this circuit passes through the exhaust thermostat 33 so that it isnot energized until such time as the exhaust air temperature rises to apredetermined high temperature. Further, in this timer motor circuit theheater cycling thermostat 32 is effective to short out the timer motoruntil such time as a predetermined high temperature of the inlet airexists. Thus both the inlet and the exhaust air temperatures must be athigh values before the timer motor is energized. This control of thetimer motor by the two thermostats results in its not being energizedwhen the operation begins, but rather becoming energized only after theclothes have substantially dried. Once the timer motor is energized, itthen begins to turn the timer cams toward the No. 1 Off position wherebyafter a short period first the heater circuit and then the drive motorcircuit are de-energized to terminate the operation of the machine.

In my preferred control all the electrical components of the controlsystem are energized from a three-wire power supply comprising thesupply conductors 46 and 47, and a neutral line 48. For domestic use itis contemplated that there will be a voltage of approximately 220 voltsbetween the supply conductors 46 and 47 and a voltage of approximately110 volts between the neutral line 48 and each of the supply conductors.

When the dial 30 is moved into the automatic range 44 and the pushbutton 35 is depressed, the circuit for energizing the drive motorv iscompleted between the supply conductor 47 and the neutral line 48.Commencing with the neutral line 48 this circuit extends through afusible link 49, a conductor 50, the timer operated switch 28 and aconductor 51 to the contacts 52 of a door switch 53. The door switch iscontrolled by the door 6 of the machine so that the contacts 52 areclosed when the door is closed and are opened when the door is open.This switch is thus efiective to break the motor circuit and halt thedrum rotation whenever the door is opened. From the contacts 52 of thedoor switch the drive motor circuit continues through a fusible link 54and a conductor 55 to the main and start windings 56 and 57 of the motor7, and from the windings 56 and 57 the motor circuit is completedthrough a conductor 58 to the supply conductor 47. As shown, the runwinding 56 is connected directly to the conductor 58 and the startwinding 57 is connected thereto through the contacts 59 of a motorcentrifugal switch 60. The centrifugal switch 60 is operated by themotor 7 and it is so arranged that the contacts 59 are closed wheneverthe motor is at rest but are opened as soon as the motor comes up tospeed. Thus the start winding 57 is connected in the circuit only untilthe motor comes up to speed. It is then removed from the circuit by thecentrifugal switch and .the motor continues to run under the action ofthe main winding alone. With the motor 7 energized through this circuit,it will be seen that it will continue to operate until such time aseither the timer operated switch 28 or the door switch contacts 52 areopened.

The heater circuit completed by setting the dial in the automatic rangeand depressing the push button 35 is energized across the supplyconductors 46 and 47. Commencing with the supply conductor 46, theheater circuit extends through a conductor 61, the timer operated switch27, and a conductor 62 to the heater cycling thermostat 32, From thethermostat 32 it proceeds through a conductor 63 to the one portion 17aof the heater.

From the portion 17a the circuit continues through the closed switch 42and a conductor 64 to a set of back contacts 65 of the motor centrifugalswitch 60. These contacts 65 are open when the motor is at rest but areclosed as soon as the motor comes up to speed. Assuming the contacts 65to be closed, the circuit is then completed through the conductor 58 tothe supply conductor 47.

Energized through this circuit, it will be seen that the heater willremain energized under the control of the cycling thermostat 32 so longas the timer operated switch 27 and the centrifugal switch contacts 65remain closed. The opening of any of these switches or contacts will,however, interrupt the heater circuit and de-energize the heater. Due tothe action of the thermostat 32 the heater is cycled intermittently soas to keep the temperature of the inlet air to the drum below thetemperature which might result in harm to sheer fabrics or synthetics.

For example, it is contemplated in one embodiment of my invention thatthe inlet air temperature will not be allowed to rise above 170 F. as aresult of the action of the cycling thermostat 32.

With the switch 42 closed and the switch 43 opened so that only theportion 17a of the heater is energized and not the portions 17b, themaximum wattage output is produced by the heater. For example in onepreferred embodiment of my invention it is contemplated that the heaterwill produce approximately 4700 watts when the portion 17a is energizedin this manner. Incidentally, it will be noted that if the drive motorshould stop rotating for any reason as for example due to the opening ofthe door 6, the heater will be de-energized due to the opening of thecentrifugal switch contacts 65. This, of course, provides for operatorsafety.

The operation of the dial 30 to the automatic range 44 and thedepressing of the auto push button 35 also closes connections for acircuit for energizing the timer motor 23. This circuit is connectedacross the supply conductors 46 and 47 but unlike the drive motor andthe heater circuits it is not energized immediately upon the initiationof the dryer operation. Rather this circuit is closed only after theclothes have substantially dried. The circuit is controlled by the jointaction of the exhaust thermostat 33 and the heater cycling thermostat 32to produce this result. Commencing with the supply line 46, the timermotor circuit extends through a conductor 66 to the timer motor 23itself, and thence it extends through conductors 67 and 68 to theexhaust thermostat 33. From the exhaust thermostat it extends throughconductors 69 and 70 to the manually operated switch 40 and thencethrough a resistor 71 to the conductor 63. The circuit is completed fromthe conductor 63 through the heater portion 17a, the switch 42, theconductor 64, the centrifugal switch contacts 65 and the conductor 53 Itwill be noted that in this circuit the timer operated switch 29 and themanually operated switch 39 are connected in parallel with the exhaustthermostat 33. However, as shown by the charts of Figs. 4 and theseswitches are both open during the automatic drying operation so that thetimer motor circuit can be closed only when the exhaust thermostat 33closes. The circuit is, however, not wholly under the control of theexhaust thermostat since the heater cycling thermostat 32 is connectedin parallel or shunt across the series combination of the timer motoritself and the exhaust thermostat. Specifically, the heater cyclingthermostat is connected in parallel with the timer motor and the exhaustthermostat by the conductor 61, the timer operated switch 27 and theconductor 62. With this arrangement of the heater cycling thermostat 32the timer motor is shorted out whenever the thermostat 32 is closed,whereby it can be energized only when the thermostat 32 is opened andthe exhaust thermostat 33 is simultaneously closed.

In the timer motor circuit the resistor 71 acts as a voltage droppingresistor to cause the proper voltage to be applied to the timer motor 23when it is energized. For example, in the illustrated embodiment for usewith a 220 volt power supply, the size of the resistor 71 is such thatwhen the thermostat 32 is open and the thermostat 33 is closed,approximately 110 volts is applied to the timer. In other words theresistance of resistor 71 cornbined with that of the heater resistor 17ais approximately equal to the impedance of the timer so that the supplyvoltage divides equally between the timer and the two resistors.

The exhaust thermostat 33 is arranged so that it closes only at anexhaust air temperature which indicates that the clothes have beensubstantially dried. As the clothes are being dried within the drum 2,the temperature within the interior of the dryer rises slowly. In fact,for a period ofthe dryer operation the amount of heat supplied to theair and the clothes from the heating element 17 may even beapproximately equal to the amount actually used for moistureextractionand duringthat period a temperature plateau will occur. This plateau orregion of very slow rise is within the generaltemperature range nomatter what type of fabrics are being dried. The dryer operates at thisplateau or with a very slow rise until such time as the clothes aresubstantially dried. Then when the clothes are substantially dried, theclothes temperature and the temperature of the exhaust air begin to risemore rapidly. The thermostat 33 is calibrated so that it closes at atemperature slightly above where this rapid temperature rise occurs. Thethermostat thereby closes the timer motor circuit only after the clothesare substantially dry.

If the heater cycling thermostat 32 is open when the exhaust airthermostat 33 closes, the timer motor is then energized and begins torotate the cams so as to terminate the machine operation. However if theheater cycling thermostat 32 should be closed, the timer motor will notbe energized until such time as it does open. Further, the timer motorcan run only so long as the thermostat 32 remains open. This actioninsures that the average temperature of the inlet air to the tumblingdrum does not decrease during the period the timer motor runs toterminate the machine operation. During this period the thermostatmaintains the inlet air at the same average temperature as during thetime before the thermostat 33 closed, and thereby the drying action maybe completed more quickly than if the control system allowed the inletair temperature to decrease. If the operation continues long enough sothat the thermostat 32 cycles the heater and timer motor inversely oneor more times, the average temperature of the exhaust air even risesslowly. Thereby the exhaust air thermostat remains closed continuouslyleaving the timer motor, in effect, under the control of the heatercycling thermostat.

The timer motor is utilized to terminate the automatic drying operationsince some additional drying time is required after the exhaustthermostat opens to dry the clothes completely, and this additionaldrying time varies depending upon the type' of fabrics being dried. Forexample heavy items such as bedspreads, shag rugs, bath towels, slipcovers, overalls, etc., take somewhat longer to finish drying after theexhaust air thermostat 33 closes than do most cottons and linens.Similarly cottons and linens take longer to dry after the exhaust airthermostat has closed than do items such as lingerie, sheer fabrics,diapers and items of various synthetic fabrics. The timer motor providesan adjustment feature whereby the operator may set the machine tooperate for a greater or lesser period after the exhaust thermostat hasclosed, thereby to obtain the proper drying eifect for the particularfabric being dried. By setting the timer control dial 30 at L (light)the timer motor will run for the least amount of time before shuttingthe machine off, by setting the dial at 'N (normal) the timer motor willrun for an intermediate length of time, and by setting the dial at H(heavy) it will run for the greatest length of time. matter what type offabrics are being dried, a correct drying effect will be provided. Ofcourse, if the load being dried includes different types of fabrics thedial may be set at points intermediate the marked positions of theautomatic range 44.

As soon as the timer motor 23 is energized it begins to drive the camstoward the off position so that first the switch 27 and then the switch28 is opened. As soon as the switch 27 is opened, the heater is turnedoff to stop the application of heat to the clothes. The switch 28 doesnot however open simultaneously with the heater switch 27. Rather itremains closed for a short time thereafter for a cool-down period.During this period the drive motor continues to operate driving theblower 9 and the drum 2 so that cool air is blown through the tumblingclothes. This reduces the temperature of the clothes and also thetemperature of the interior of the dryer so that the operator may removethe clothes from the machine without discomfort. The cool-down pe- Inthis manner it is insured that no ried is terminated when the timeropens switch 28 so as to deenergize the drive motor 7. The de-energizingof the drive motor terminates the operation of the machine completelyand the operator may then open the door 6 and remove the fully driedclothes.

Since the timer motor circuit passes through the contacts 65 of themotor centrifugal switch 60, the de-energizing of the driver motor bytimer switch 28 also terminates the operation of the timer motor. Thecontacts 65 are opened as the drive motor stops rotating, and therebythe timer 23 is de-energized so that all the electrical components ofthe machine are removed from operation.

During the period that the timer motor is running before the cool-downperiod begins, the temperature in the interior of the dryer decreasesslowly so long as the heater cycling thermostat 32 is open. If thistemperature, or more accurately the inlet air temperature, should dropto a certain predetermined lower value before the heater switch 27 isopened, the heater cycling thermostat 32 will close so as to re-energizethe heater and shunt the timer motor. The heater then continues inoperation with the timer motor off until such time as the predeterminedhigher temperature is reached at which time the heater cyclingthermostat again opens. At that time the heater is again removed fromoperation and the timer placed back in operation to move the cams towardthe machine shut-down position. The heater and the timer may thus becycled inversely one or more times before the dryer operation is finallyterminated. This action causes the clothes to be tumbled long enough andat the right temperature to insure their drying, with the averagetemperature within the dryer not dropping during the period.

If the dial is set in the L (light) position of the automatic range thetimer normally shuts down the dryer before the temperature falls to thepoint where the heater cycling thermostat re-energizes the heater. Thusthere is usually no inverse cycling of the heater and the timer when thedial is set at the L (light) position. If, however, the dial is set inthe N (normal) or H (heavy) positions of the automatic range it iscontemplated that the thermostat may cycle the timer and the heaterinversely one or more times before the dryer operation is terminated.

Besides the above-described automatic drying operation my improvedcontrol system also provides for a timed clothes drying operation and atimed sprinkling operation. For either of these operations the dial 30is set within the time range 45, the position within the time rangebeing selected according to the amount of time that is desired for themachine to operate. Then if it is desired to dry clothes, either thebutton 36 or the button 37 is depressed. If it is desired to apply amaximum amount of heat to the clothes, the button 36 is depressed,whereas if it is desired to apply a lesser amount of heat to theclothes, the button 37 is depressed. The button 37 for the lower heatingsetting is ordinarily depressed when it is desired to dry synthetics andother delicate fabrics which might be injured if heated too rapidly orto too high a temperature. If it is desired to tumble the clotheswithout heat, for example for sprinkling purposes, then the button 38 isdepressed.

Assuming that it is desired to dry clothes for a timed period under highheat, and that the dial 30 has been set and the button 36 has beendepressed to effect this result, then circuits are completed for thedrive motor, the heater and the timer as follows. The heater circuit andthe drive motor circuit are identical with those described above for theautomatic drying operation. In other words the heater is energized bythe circuit through the timer operated switch 27 and the heater cyclingthermostat 32, and the drive motor is energized by the timer operatedswitch 28. The timer motor is however energized by a diiferent circuitso that it is energized continuously during this operation. The timermotor circuit extends between the conductor 46 and the neutral line 48by means of the timer operated switch 28 andthe manually operated switch41. Commencing with the supply conductor 46 the timer circuit extendsthrough .conductor 66 and the timer motor 23 to conductor 67 and thencethrough the switch 39, which is now closed, to the conductor 70. Fromthe conductor 70 it continues through the conductor 72 to the manuallyoperated switch 41, which is also now closed, and from the switch 41 itextends through conductor 73 and fusible link 54 to the contacts 52 ofthe door switch. From the door switch it is completed through conductor51, timer operated switch 28, conductor 50 and fusible link 49 to theneutral line 48.

Energized through this circuit it will be seen that the timer motor willcontinue in operation until such time as the timer operated switch 28 isopened. The switch 28 as shown by the cam chart is opened only at theend of the operation so that the timer motor thus runs continuously toprovide an operation of timed length. Incidentally, it will be notedthat the opening of the door switch de-energizes the timer motorsimultaneously with the drive motor, whereby only the periods that themachine is in operation are counted by the timer mechanism.

Referring to the cam chart of Fig. 4 it will be noted that the switch 27is opened slightly before the switch 28 in this timed drying operation.Thus there is a cooldown period provided in the timed clothes dryingoperation just as in the automatic clothes drying operation.

If it is desired to operate the dryer with the heater operating at itslower level of energization, then the push button 37 is operated insteadof the push button 36. The result of this operation of the button 37 isthat the switch 42 is opened while the switch 43 is closed, and thatplaces the heater portion 17b in series with the heater portion 17a inthe heater circuit. With the switches so operated the heater circuitextends through heater portion 17a and 17b in series, and then is joinedto the line 64 through the conductor 74 and the switch 43. The placingof the heater portion 17b in series with the portion 17a results in theheater presenting greater resistance whereby there is less wattageoutput from it. As a result of the heater operating at a lower level,the temperature Within the dryer rises more slowly whereby the heatermay even continue in operation throughout the entire drying cyclewithout ever being cycled on and off by the heater cycling thermostat32. In other words the inlet air may never be raised to a temperature atwhich the cycling thermostat will open the heater circuit. However, ifthe temperature does rise to that point, the thermostat 32 will cyclethe heater in the usual manner. The drive motor and timer motor circuitsremain the same as during the high temperature timed drying operationsince the switches 39 and 41 are closed no matter which heat button 36or 37 is depressed.

If it is desired to tumble clothes without heat, for example forsprinkling them, the dial 30 is again set in the time range 45, but thesprinkle push button 38 is depressed rather than either of the dryingpushbuttons 36 and 37. As shown in Fig. 5 the depressing of the sprinklepush button closes'the switches 39 and 41 and leaves the remainingswitches 40, 42 and 43 open. The opening of the switches 42 and 43breaks the heater circuit where by the heater cannot be energized at anytime. However, the same drive motor and timer motor circuits arecompleted as during the timed drying operation. Thus the timer motor andthe drive motor are both energized, the drive motor causing rotation ofthe drum and the passage of air through the drum and the timer motortiming the length of the operation. The operation is terminated at suchtime as the timer motor rotates the cam 25 far enough to open the switch28 and break both circuits.

From the above it will be seen that my new and improved control systemprovides for three different operations of a clothes drying machine.Firstly, it provides for a temperature controlled drying operation whoselength is automatically controlled so as to produce fully dried clothes.In this automatic operation the control of the timer motor by the twothermostats, one responsive to the inlet air and the other responsive tothe exhaust air, produces a particularly eflicient control bothmaintaining the inlet air temperature high for quick drying and insuringthat the dryer operation is terminated at the proper time. The controlsystem also provides for a timed drying operation wherein the dryer maybe set to operate for a predetermined length of time. In this timeddrying operation the heater may be energized at two different levels soas to give greater flexibility of the effects obtained. Further, thecontrol system provides for a clothes tumbling operation without heatwhich may advantageously be used for sprinkling or fiuffing clothes.

It is, of course, realized that the operator may at times make a mistakewhen she sets the controls of the dryer. For example, she might set thedial in the automatic range 44 and depress one of the buttons 36, 37 or38 instead of depressing the automatic push button 35. Conversely, shemight set the dial in the time range 45 and depress the automatic pushbutton 35. However, no matter how she may mis-set the dial or the pushbuttons, the machine will still time itself out. In other words thetimer motor 23 will still be energized so as to turn the timer camstoward an off position. If the operator should set the dial in theautomatic range and then depress any one of the high, low, or sprinklepush buttons 36, 37 or 38 the timer motor will be energized by a circuitthrough switches 39 and 41. With the dial set in the automatic range thetimer operated switch 29 is open, but the depressing of any one of thepush buttons 3638 closes the switches 39 and 41 and opens switch 40.That completes a timer motor circuit across conductor 46 and neutralline 48. Commencing with conductor 46 this circuit comprises conductor66, the timer motor itself, conductor 67, switch 39, conductors 70 and72, switch 41, conductor 73, fusible link 54, door switch contacts 52,conductor 51, timer operated switch 28, conductor 50 and fusible link49. This circuit remains until such time as cam 25 opens switch 28,whereupon it is opened simultaneously with the drive motor circuit toterminate machine operation.

Oppositely, if the operator should set the dial in the time range 45 butdepress the automatic push button 35, then the switches 39, 41 and 43would be open and switches 40 and 42 closed. The timer circuit of theprevious possible mis-setting thus cannot be completed. However, withthe timer set in the time range, the timer operated switch 29 is closedso that the timer will be connected across the heater cycling thermostatby conductor 66, switch 29, conductor 70, switch 40 and the resistor 71.Thus no matter what the condition of the exhaust air thermostat 33, assoon as the heater cycling thermostat opens, the timer will be driventoward the off position; and therefore no matter how the operatormissets the controls, the timer will ultimately reach an oft positionand terminate the machine operation.

Besides those components already described, it will be noted that my newand improved control system includes an ozone lamp 75 for freshening theair inside the dryer and a light 76 for illuminating the interior of thedryer. The ozone lamp and the illuminating light are connected in seriesand are energized whenever the machine is in operation and also wheneverthe door is opened. When the machine is in operation, they are energizedbetween the neutral line 48 and the supply conductor 47 by a circuitthrough the timer operated switch 28. Commencing with the neutral line48, this circuit extends through the fusible link 49, the conductor 50,the timer operated switch 28 and the conductor 51 to the illuminatinglamp 76. It then extends through the lamps 76 and 75 in series to theconductor 47. When the door is opened, the lamp circuit is thencompleted through a set of back contacts 77 of the door switch. Thiscircuit like the other circuit is energized between the neutral line 48and the conductor 47. Commencing with the line 48, the circuit extendsthrough the fusible link 49, the conductor 50 and another conductor 78to the back contacts 77 of the door switch. It then extends through thecontacts 77 to the lamp 76 and then through the lamp in series to theconductor 47. Since the contacts 77 are closed whenever the door isopened, it will thus be seen that the lamps are energized whenever thedoor is open as well as when the dryer is in operation.

While in accordance with the patent statutes I have described what atpresent is considered to be the preferred embodiment of my invention itwill be obvious to those skilled in the art that various changes andmodifications may be made therein without departing from my invention,and I, therefore, aim in the appended claims to cover all such changesand modifications as come within the true spirit and scope of myinvention.

What I claim as new and wish. to secure by Letters Patent of the UnitedStates is:

1. In a clothes dryer having clothes tumbling means, a drive motor fordriving said tumbling means, a heater, and blower means for blowing airover said heater and through said tumbling means for drying the clothesthere in, a control system for producing selectively a timed clothesdrying operation, a temperature controlled clothes drying operation ofautomatically controlled length, and a timed clothes tumbling operationwithout heat, said control system comprising a timer mechanism includinga timer and switch means operated by said timer, a heater cyclingthermostat responsive to the temperature of the inlet air entering saidtumbling means from said heater, an exhaust air thermostat responsive tothe temperature of the exhaust air leaving said tumbling means, a heatercircuit including said heater cycling thermostat for energizing saidheater during both of said clothes drying operations, a drive motorcircuit including timer operated switch means for energizing said drivemotor continuously during all three of said operations, a first timercircuit including timer operated switch means for energizing said timercontinuously during both said timed clothes drying operation and saidtimed clothes tumbling operation, a second timer circuit including saidexhaust air thermostat for energizing said timer during said temperaturecontrolled clothes drying operation, with said timer being de-energizedat the beginning of said temperature controlled clothes drying operationand being energized only after the exhaust air reaches a pre-determinedhigh temperature, and manually operable means for selectively adjustingsaid control system to obtain the desired one of said operations, saidexhaust air thermostat and said timer being interconnected with saidheater cycling thermostat so that said timer can be energized by saidexhaust air thermostat during said temperature controlled dryingoperation only when said heater cycling thermostat is open.

2. In a clothes dryer having clothes tumbling means, a drive motor fordriving said tumbling means, a heater, and means for blowing air oversaid heater and through said tumbling means for drying the clothestherein, a control system for producing selectively a timed clothesdrying operation, a temperature controlled clothes drying operation ofautomatically controlled length and a timed clothes tumbling operationwithout heat, said control system comprising a timer mechanism includinga timer and switch means operated by said timer, a heater cyclingthermostat responsive to the temperature of the inlet air entering saidtumbling means from said heater, an exhaust air thermostat responsive tothe temperature of the exhaust air leaving said tumbling means, a heatercircuit including said heater cycling thermostat for energizing saidheater during both of said clothes drying operations, a drive motorcircuit including timer operated switch means for energizing said drivemotor continuously during all three of said operations, a plurality ofmanually operated switches, a first timer circuit including timeroperated switch means and at least one of said manually operatedswitches for energizing said timer continuously during both said timedclothes drying operation and said .tion, and circuit meansinterconnecting said exhaust air thermostat and said timer with saidheater cycling thermostat so that said timer can be energized by saidexhaust air thermostat during said temperature controlled dryingoperation only when said heater cycling thermostat is open, and manuallyoperable means for adjusting said timer mechanism and said manuallyoperated switches to arrange said system to obtain the desired one ofsaid operations.

3. The combination of claim 2 wherein said timer includes an automaticrange for said temperatures controlled operation and a time range forboth of said timed operations, and said manually operable means comprisea rotatable dial for adjusting said timer mechanism into said ranges anda plurality of push buttons for adjusting said manually operableswitches.

4. The combination of claim 2 wherein said heater circuit includes apair of said manually operable switches for energizing said heater atdifferent levels during said timed drying operation, thereby to produceselectively a low heat operation and a high heat operation.

5. In a clothes dryer having clothes tumbling means, a heater, blowermeans for blowing air over said heater and through said clothes tumblingmeans for drying clothes therein, and a drive motor for driving saidtumbling means, a control system for producing selectively a timedclothes drying operation, a temperature controlled clothes dryingoperation of automatically controlled length, and a timed clothestumbling operation without heat, said control system comprising a timermechanism including a timer and a plurality of switches operated by saidtimer, a heater .cycling thermostat responsive to the temperature of theinlet air entering said tumbling means from said heater, an exhaust airthermostat responsive to the temperature of the exhaust air leaving saidtumbling means, a normally open centrifugal switch operated by saidmotor, a heater circuit including one of said timer operated switchesand said heater cycling thermostat for energizing said heater duringboth of said clothes drying operations, a drive motor circuit includinga second of said timer operated switches for energizing said drive motor4 continuously during all three of said operations, a plurality ofmanually operable switches, a first timer circuit for energizing saidtimer continuously during said timed clothes drying operation and saidtimed clothes tumbling operation, said first timer circuit includingsaid second timer operated switch and at least one of said manuallynperated switches, a second timer circuit for energizing said timerduring said temperature modified clothes drying operation, said secondtimer circuit including said ex,- haust air thermostat, said heater, oneof said manually operated switches and said centrifugal switch, andmeans for selectively adjusting said timer mechanism and said manuallyoperable switches to connect said control system to obtain the desiredone of said operations.

6. The combination of claim 5 wherein said exhaust air thermostat andsaid timer motor are connected in series circuit relation across saidheater cycling thermostat so that said timer motor can be energizedduring said temperature controlled clothes drying operation only whensaid exhaust air thermostat is closed and said heater cycling thermostatis open.

7. In a clothes dryer having clothes tumbling means, a drive motor fordriving said tumbling means, a heater, and blower means for blowing airover said heater and through said clothes tumbling means for drying theclothes therein, a control system comprising a timer mechanism having atimer motor and switch means operated by said timer motor forcontrolling said heater and said drive motor, an inlet air thermostatfor cycling said heater in response to the temperature of the inlet airentering said tumbling means from said heater, an exhaust air thermostatresponsive to the temperature of the exhaust air leaving said drum forcontrolling said timer motor, and circuit means connecting said inletair thermostat in parallel circuit relation with said timer motor sothat said timer motor can be energized by said exhaust air thermostatonly when said inlet air thermostat is open.

8. In a clothes dryer having clothes tumbling means, a heater, blowermeans for blowing air over said heater through said tumbling means fordrying the clothes therein and a drive motor for driving said tumblingmeans and said blower means, a control system comprising a timermechanism having a timer motor and switch means operated by said timermotor for controlling said heater and said drive motor, an inlet airthermostat for cycling said heater in response to the temperature of theinlet air entering said tumbling means from said heater, an exhaust airthermostat responsive to the temperature of the exhaust air leaving saidtumbling means for controlling said timer motor, and circuit meansconnecting said exhaust air thermostat and said timer motor in a shuntcircuit across said inlet air thermostat so that said timer motor can beenergized only when said exhaust air thermostat is closed and said inletair thermostat is open.

9. In a clothes dryer having clothes tumbling means, a drive motor fordriving said tumbling means, a heater and blower means for blowing airover said heater and through said clothes tumbling means for drying theclothes therein, a control system comprising a timer mechanism having atimer motor and switch means operated by said timer motor forcontrolling said heater and said drive motor, an inlet air thermostatfor cycling said heat er in response to the temperature of the inlet airentering said tumbling means from said heater, an exhaust air thermostatresponsive to the temperature of the exhaust air leaving said drum, anormally open centrifugal switch driven by said drive motor, and acircuit for energizing said timer motor including said exhaust airthermostat and said motor centrifugal switch, with said timer motorcircuit being opened by centrifugal switch when said drive motor isde-energized by said timer operated switch means at the close of theclothes drying operation.

10. In a clothes dryer having clothes tumbling means, a drive motor fordriving said tumbling means, and a heater for heating the clothes beingtumbled to dry said clothes, a control system comprising a timermechanism having a timer motor and switch means operated by said timermotor for controlling said heater and said drive motor, a normally openswitch closed in response to therotation of said drive motor, and acircuit for energizing said timer motor including said normally openswitch, with said timer motor circuit being de-energized by said switchwhen said drive motor is de-energized by said timer operated switchmeans at the close of the clothes dryer operation.

11. In a clothes dryer having clothes tumbling means, a drive motor fordriving said tumbling means, a heater,

and blower means for blowing air over said heater and through saidtumbling means for drying the clothes therein, a control system forproducing selectively a timed clothes drying operation and a temperaturecontrolled clothes drying operation. of automatically controlled length,said control system comprising a timer mechanism including a timer andswitch means operated by said timer, a heater cycling thermostatresponsive to the temperature of the inlet air entering said tumblingmeans from said heater, an exhaust air thermostat responsive to thetemperature of the exhaust air leaving said tumbling means, a heatercircuit including timer operated switch means and said heater cyclingthermostat for energizing said heater during both of said operations, adrive motor circuit including timer operated switch means for energizingsaid drive motor continuously during both of said operations, a firsttimer circuit including timer operated switch means for energizing saidtimer motor continuously during said timed clothes drying operation, asecond timer circuit ineluding switch means operated by said timer andsaid exhaust air thermostat for energizing said timer during saidtemperature controlled clothes drying operation, with said timer beingde-energized at the beginning of said temperature controlled dryingoperation and being energized by said exhaust thermostat only after theexhaust air reaches a predetermined high temperature, said timerincluding presettable means for varying its period of operation in saidtemperature controlled operation after it is energized by said exhaustthermostat, and manually operable means for selectively adjusting saidcontrol system to obtain the desired one of said operations.

12. In a clothes dryer having clothes tumbling means, a drive motor fordriving said tumbling means, a heater, and blower means for blowing airover said heater and through said clothes tumbling means for drying theclothes therein, a control system for producing selectively a timedclothes drying operation and a temperature controlled clothes dryingoperation of automatically controlled length, said control systemcomprising a timer mechanism including a timer and switch means operatedby said timer, a heater cycling thermostat responsive to the temperatureof the inlet air entering said tumbling means from said heater, andexhaust air thermostat responsive to the temperature of the exhaust airleaving said tumbling means, a heater circuit including timer operatedswitch means and said heater cycling thermostat for energizing saidheater during both of said operations, a drive motor circuit includingtimer operated switch means for energizing said drive motor continuouslyduring both of said operations, a plurality of manually operatedswitches, a first timer circuit including timer operated switch meansand one of said manually operated switches for energizing said timercontinuously during said timed clothes drying operation, a second timercircuit including said exhaust air thermostat and a second of saidmanually operated switches for energizing said timer during saidtemperature controlled clothes drying operation, means connecting saidheater cycling thermostat in parallel circuit relation with said timerin said second timer circuit so that said timer can be energized by saidexhaust air thermostat during said temperature controlled dryingoperation only when said heater cycling thermostat is opened, andmanually operable means for adjusting said timer mechanism and saidmanually operated switches to select the desired one of said operations.

References Cited in the file of this patent UNITED STATES PATENTS2,654,961 Manecke Oct. 13, 1953 25 2,707,837 Robinson et al. May 10,1955 2,717,455 Harris et al. Sept. 13, 1955

